Carburetor fuel bowl inlet arrangement



Feb. 17, 1970 v c. EL'AM I 3,495,809

' v CARBURETOR FUEL BOWL INLET ARRANGEMENT Filed Jan. 26, 1968 TO PRESSURE RESPONSIVE INLET VALVE v. .Aw

INVENTOR.

ATTORNEY United States Patent 3,495,809 CARBURETOR FUEL BOWL INLET ARRANGEMENT Charles F. Elam, Rochester, N.Y., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Jan. 26, 1968, Ser. No. 700,814 Int. Cl. F02m 1 7/00 U.S. Cl. 26167 3 Claims ABSTRACT 0F THE DISCLOSURE A fuel supply system for a carburetor wherein the flow of fuel from a fuel source to a constant level fuel bowl is controlled by a pair of valves. The first valve is controlled by a float while the opening and closing of the second valve is regulated by a pressure responsive piston valve which is fluidly connected to the mixture conduit of the carburetor. At a predetermined subatmospheric pressure condition in the mixture conduit, the piston valve is actuated thereby permitting the associated valve to move to an open position wherein fuel flows through a secondary inlet into the fuel bowl.

Under normal operating conditions, the constant level fuel bowl, commonly used in carburetors, receives and maintains a sufficient supply of fuel through a single float valve controlled inlet port. However, in certain instances such as rapid acceleration or high speed operation, the demand for fuel increases significantly due to the higher air flow required to sustain this type of engine performance. To insure that these supply requirements can be met, a single float valve and associated inlet must be designed to satisfy both normal and maximum fuel demands. However, inasmuch as the high demand periods arise infrequently, the supply of the additional fuel can more easily be regulated by providing a secondary inlet port for these occurrences.

In the prior art, certain devices have'been proposed that use a second float-controlled valve. However, the added valve is usually designed to open only after the fuel level has dropped below a predetermined level. Thus, the supplemental supply of fuel will lag behind the demand of the engine. The present invention, on the other hand, provides a secondary valve the opening of which is controlled, in the preferred form, by a piston valve responsive to the air flow and pressure conditions within the carburetor mixture conduit. The piston valve is fluidly connected by an air bleed conduit to the mixture conduit of the carburetor and, under conditions when the demand for fuel increases due to higher air and fuel flows, this conduit transmits the air flow and pressure conditions to the piston valve cylinder which, in turn, shifts the piston and permits the secondary valve to shift to an open condition under the pressure of the fuel in the discharge line. Thus, whenever conditions of high air flow and subatmospheric pressure exist in the carburetor mixture conduit, an additional fuel inlet port is provided for the fuel bowl thereby assuring an adequate supply of fuel substantially as soon as a demand arises.

Accordingly, the objects of the present invention are: to provide a fuel supply system for a constant level carburetor fuel bowl wherein the supply of fuel thereto is regulated by a pair of valves; to provide a fuel bowl inlet supply system for a carburetor wherein a secondary fuel inlet port is opened concurrently with the demand for increased amounts of fuel; to provide a secondary fuel supply system for a carburetor fuel bowl during engine operating conditions requiring a high volume fuel consumption; to provide a carburetor fuel bowl supply syslCC tem wherein a float controls a first valve to regulate the supply of fuel to the bowl under normal engine operating conditions, and a second valve, responsive to air flow and pressure conditions in the carburetor, provides a secondary fuel inlet supply passage under engine operating conditions that require high volume fuel consumption; and to provide a carburetor fuel bowl inlet valving arrangement wherein a float valve maintains the fuel level in the fuel bowl at a predetermined level and supplies fuel demands of the engine during normal operating conditions and wherein an auxiliary valve, controlled by a means movable in response to air flow and pressure conditions in the carburetor mixture conduit, provides a secondary fuel inlet to the fuel bowl under engine operating conditions that require a high volume fuel consumption.

These and other objects will be apparent to one skilled in the art upon reading the following detailed description, reference being made to the accompanying drawings in which:

FIGURE 1 is a schematic illustration of a carburetor having primary and secondary mixture conduits provided with the pressure responsive air bleed conduit of the present invention; and

FIGURE 2 is a side cross-sectional view of a carburetor fuel bowl incorporating the dual fuel bowl valve arrangement made according to the present invention.

Referring to FIGURE 1, there is shown a schematic view of a conventional carburetor having a primary mixture conduit 10 and a secondary mixture conduit 12. As should be apparent, the carburetor is adapted to be connected to the intake manifold of an internal combustion engine and supply fuel thereto. The primary mixture conduit 10 includes a venturi section 14 through which the flow of air and fuel is regulated by a primary throttle 16. The flow of air and fuel through the secondary mixture conduit 12 is controlled by an air valve 18 and a secondary throttle 20. The primary throttle 16 is interconnected by a suitable control linkage (not shown) to the air valve 18 and the secondary throttle 20 in a manner such that the latter remains in the illustrated closed position until the primary throttle 16 opens a predetermined amount. Thereafter, the air valve 18 and the secondary throttle 20 begin to open and a combustible mixture of fuel and air flows through the secondary mixture conduit 12 as well as the primary mixture conduit 10. The carburetor also includes an air bleed conduit or passageway 22 provided with branches 24 and 26. Branch 24 registers with the venturi section 14 of the primary mixture conduit 10 while branch 26 registers with the secondary mixture conduit 12 at a location between the air valve 18 and the secondary throttle 20.

Referring now to FIGURE 2, there is shown a carburetor fuel supply system incorporating the persent invention and which, more specifically, includes a fuel bowl housing 28 defining an interior fuel reservoir 30. A fuel bowl cover 32 is sealingly attached to the upper rim of the fuel bowl housing 28 by any suitable means. Within the fuel reservoir is a float 34 secured to a float control arm 36. The control arm 36 is pivotally supported by a pin connection 38 from a bracket 40 formed integrally on the underside of the fuel bowl cover 32. An end section 42 of the float control arm 36 bears directly on the top end portion of a primary valve 44 which is slidably received within a cylindrical chamber 46. The primary valve 44 includes a conical tip portion 48 adapted to seat upon closing within a primary fuel inlet port 50. A secondary valve 52 is slidably retained within a cylindrical chamber 54 and is controlled by a pressure responsive piston valve, generally indicated by the reference numeral 56. The secondary valve 52 similarly includes a conical tip portion 58 adapted to seat within a secondary fuel inlet port 60. The inlet ports and 60 are in fluid communication with a fuel discharge passage 62 that is supplied with fuel under pressure from a fuel pump, not shown, through a fuel line 64.

The pressure responsive piston valve 56 generally comprises a reciprocable piston 66, slidably retained within a cylinder 68, and a rod 70 attached at one end to the piston 66 and at the other end to an abutment disk 72. A coil spring 74 is compressively retained between the abutment disk 72 and a stop collar 76, press-fitted withing a shouldered bore 78 formed in the float bowl cover 32 coaxially with the piston cylinder 68. The coil spring 74 biases the piston valve 56 downwardly to the illustrated position wherein the abutment disk 72 engages the secondary valve 52 and seats the conical tip portion 58 within the secondary fuel inlet port 60. The piston cylinder 68 is fluidly connected to the air bleed conduit 22 so that pressure conditions in the secondary mixture conduit 12 and the primary mixture conduit are transmitted to the piston cylinder 68.

Under normal engine operating conditions, the primary valve 44 is controlled by the float 34 in a well known manner wherein, as the fuel level in the fuel reservoir 30 drops below a predetermined level, the float 34 rotates downwardly about pin 38 thereby permitting the primary valve 44 to move upwardly under the pressure of the fuel in the discharge line 62 and, consequently, fuel flows through the primary fuel inlet port 50 into the reservoir. As fuel is supplied to the reservoir 30, the float moves upwardly, and the control arm 36 seats the conical tip portion 48 against the primary fuel inlet port 50 when the fuel level again reaches the predetermined level. With the throttle 16 partially opened, the air flow past the venturi section 14 produces a subatmospheric pressure condition in the branch 24. This pressure condition, in turn, is transmitted through the air bleed conduit 22 to the piston cylinder 68. As the subatmospheric conditions in the cylinder 68 reach a predetermined value, the compressive force of the spring 74 is overcome and the piston valve 56 gradually shifts upwardly thereby permitting the secondary valve 52 to move to an open position wherein fuel from the discharge line 62 enters the fluid reservoir 30 through the secondary inlet port 60. After the primary throttle 16 is opened beyond a predetermined amount, the secondary throttle and the air valve 18 open and a pressure drop occurs across the air valve 18. This subatmospheric pressure differential is transmitted through branch 26, cumulatively with the pressure conditions at the branch 24, to regulate the movement of the piston valve 56. By properly sizing and placing the components operatively associated with the piston valve 56, a secondary fuel supply passage is provided for the fuel reservoir 30 such that an adequate supply of fuel will be available under all engine operating conditions.

What is claimed is:

1. A carburetor for an internal combustion engine, comprising: a housing having a mixture conduit including a venturi section and a fuel reservoir; a discharge line containing fuel under pressure; a pair of inlet ports formed in the housing and fluidly connecting the fuel reservoir with the discharge line; first and second valve means registering with the inlet ports and adapted to open and close the inlets; a float in the fuel reservoir operably connected to the first valve means and adapted to move the latter to close the associated inlet when the fuel in the reservoir reaches a predetermined level and permitting the fuel under pressure in the fuel discharge line to move the first valve means to an open position when the fuel in the reservoir drops below said predetermined value; pressure responsive means normally biasing the second valve means to a closed position and movable in response to subatmospheric pressure conditions to a position wherein said second valve means is unrestrained and movable to an open position by the pressure of the fuel in the fuel discharge line; conduit means operatively connecting the venturi section of the mixture conduit and the pressure responsive means, said conduit means transmitting subatmospheric pressure conditions at the venturi section to actuate said pressure responsive means and permit fuel flow through the inlet associated with the second valve means to the fuel reservoir thereby providing an auxiliary fuel inlet supply passageway under conditions of high fuel consumption.

2. A carburetor for an internal combustion engine, comprising: a housing having a mixture conduit including a venturi section and a fuel reservoir; a discharge line containing fuel under pressure; a pair of inlets formed in the housing and fluidly connecting the fuel reservoir with the discharge line; first and second valve means registering with the inlets and adapted to move between an open position wherein fuel flows through the inlets to the fuel reservoir and a closed position wherein the flow of fuel from the discharge line to the fuel reservoir is obstructed; a float in the fuel reservoir operably connected to the first valve means and adapted to move the latter to close the associated inlet when the fuel in the reservoir reaches a predetermined level and permitting the fuel in the discharge line to move the first valve means to said open position when the fuel in the reservoir drops below said predetermined level; a pressure responsive piston valve including a piston and an associated piston cylinder normally biasing the second valve means to the closed position and movable in response to subatmospheric pressure conditions in the piston cylinder to a position wherein said second valve means is unrestrained and movable to said open position by the pressure of the fuel in the discharge line; conduit means operatively connecting the venturi section and the piston cylinder, said conduit means transmitting subatmospheric pressure conditions at the venturi section to actuate said piston valve and permit fuel flow through the inlet associated with the second valve means to the fuel reservoir thereby providing an auxiliary fuel inlet supply passageway under conditions of high fuel consumption.

3. A carburetor for an internal combustion engine, comprising: a housing having a primary mixture conduit including a venturi section, a secondary mixture conduit and a fuel reservoir, said primary mixture conduit having a primary throttle downstream of said venturi section for controlling the passage of air and fuel therethrough, said secondary mixture conduit having an air valve and a secondary throttle operatively connected to the primary throttle; a discharge line containing fuel under pressure; a pair of inlet ports formed in the housing and fluidly connecting the fuel reservoir with the fuel discharge line; first and second valve means registering with the inlet ports and adapted to move between an open position and a closed position; a float in the fuel reservoir operably connected to the first valve means and adapted to move the latter to close the associated inlet when the fuel in the reservoir reaches a predetermined level while permitting the fuel under pressure in the fuel discharge line to move the first valve means to said open position when fuel in the reservoir drops below said predetermined level; a pressure responsive piston valve including a piston and an associated cylinder normally biasing the second valve means to the closed position and movable in response to subatmospheric pressure conditions in the cylinder to a position wherein said second valve means is unrestrained and movable to said open position by the pressure of the fuel in the discharge line; an air bleed conduit fluidly connecting the carburetor and the pressure responsive piston valve, said conduit including a first branch communicating with the primary mixture conduit at the venturi section and a second branch communicating with the secondary mixture conduit between the air valve and the secondary throttle whereby said air bleed conduit transmits subatmospheric pressure conditions at the primary and secondary mixture conduits to the piston cylinder to actuate said pressure responsive piston valve and permit fuel flow through the in et associated with the 5 6 second valve means to the fuel reservoir under conditions 2,937,014 5/1960 Klaber 261-72 of high fuel consumption. 2,989,065 6/1961 McDuffie 261-69 X References Cited 3,052,453 9/1962 Carlson 261-72 UNITED STATES PATENTS 5 TIM R. MILES, Primary Examiner 1,712,460 5/1929 Purdy et a1 26170 S 1 X 1,872,555 8/1932 Ball at al. 261-72 X 2,801,645 8/1957 White 261-72 X 261-69, 73 

